Q239 / 270 · NDA 2020 · Mathematics

The sum of deviations of $n$ number of observations measured from 2.5 is 50 . The sum of deviations of the same set of observations measured from 3.5 is -50 . What is the value of $n$ ?

  • A
    50
  • B
    60
  • C
    80
  • Correct answer
    D
    100

Solution

Number of data set $=n$. Mean $=2.5$ Sum of deviations $=50$ Again, sum of deviations, when mean $=3.5$ is -50 . So, $(3.5-2.5) \times n=50-(-50)$ $\therefore n=100$

Hence, the correct answer is option: 'D'.

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